GOP presidential contender Mitt Romney greets attendees at the National Association of Latino Elected and Appointed Officials conference, Thursday, June 21, 2012, at the Contemporary Resort at Walt Disney World, in Lake Buena Vista, Florida. (Joe Burbank/Orlando Sentinel/MCT)

Photo: Joe Burbank, McClatchy-Tribune News Service

GOP presidential contender Mitt Romney greets attendees at the...

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Bryan Munks, 19, of Arlington, Va., makes calls for the Romney campaign while wearing a quick response code sticker, or QR, in Fairfax, Va., on Tuesday, June 19, 2012. The presidential ground game has gone high tech, marrying old-school organizing work with innovative digital tools. The T-shirts that Romney campaign volunteers wear in Virginia feature a digital code that voters can zap with their smart phones to learn more about the Republican presidential hopeful, which gives Romney field organizers valuable information on how to reach them in the future.(AP Photo/Jacquelyn Martin)

Backing off the harsh rhetoric of the Republican primaries, Mitt Romney pledged Thursday to address illegal immigration "in a civil but resolute manner." He outlined plans to overhaul the green card system for immigrants with families, and end immigration caps for their spouses and minor children.

In a speech before Latino leaders, Romney made only passing mention of his promise to complete a 2,000-mile border fence to help stem illegal immigration. Instead, he attacked President Obama's new plan to ease deportation rules for some illegal immigrants brought to the United States as children as little more than a stopgap measure.

"As president, I won't settle for a stopgap measure. I will work with Republicans and Democrats to find a long-term solution," Romney told the National Association of Latino Elected and Appointed Officials. "I will prioritize measures that strengthen legal immigration and make it easier. And I will address the problem of illegal immigration in a civil but resolute manner. We may not always agree, but when I make a promise to you, I will keep it."

Obama will speak to the same group Friday. The speeches come as the Supreme Court prepares to render judgment on a get-tough Arizona law and after Obama announced his new deportation plan.

Romney again refused to say whether he would reverse Obama's policy, promising his "own long-term solution that will replace and supersede the president's temporary measure."

The former Massachusetts governor has struggled in recent days to clarify his immigration policy as he pivots from the sharp tone that defined the months-long GOP primary to a general election audience in which Latinos will play a critical role.

At least 1 in 6 Americans is of Latino descent, according to the Census Bureau, and many lean toward the Democrats. By softening his tone on immigration, Romney is looking to narrow the advantage that Obama has with this pivotal constituency.

Romney was vague in some areas - particularly the treatment of immigrant children brought to the country illegally by their parents - but offered new details in others.

His plan to reallocate green cards for immigrants with families and end caps for spouses and minor children would mark a change from the current system, which is something of a first-come, first-served system. And his pledge to "staple a green card to your diploma" for immigrants who earned advanced degrees in the United States represents a significant change from current law.

It is unclear how many of Romney's promises on immigration reform - such as granting green cards to high-tech graduates - could be accomplished without congressional action.